Fast Analysis of Periodic Antennas and Metamaterial-Based Waveguides

A tailored version of the Characteristic Basis Function Method (CBFM) is presented as a matrix compression technique for the method-of-moments (MoM) to rapidly compute the impedance, radiation, and propagation characteristics of large periodic structures, including antenna arrays and metamaterial-based waveguides. The compression is achieved by employing physics-based Characteristic Basis Functions (CBFs), which are generated numerically and in a time-efficient manner by exploiting array symmetries. The supports of these CBFs partially overlap between electrically interconnected array elements to preserve the continuity of the surface current across common boundaries. The translation symmetry is also exploited to expedite the meshing process of the structure, to construct the reduced matrix equation, and to rapidly compute the antenna radiation patterns. The Adaptive Cross Approximation (ACA) algorithm is applied to reduce the matrix fill-time even further. The numerical examples demonstrate high accuracy and excellent memory compressing capabilities of the considered method. Among the problems, we consider a very large array of nested subarray antennas employing more than 1E6 low-level basis functions, which is solved directly, in-core, through a multilevel CBFM approach, and we analyze a metamaterial-based gap waveguide through a CBFM-enhanced MoM approach employing the parallel-plate Green’s function